Selective lithium extraction from brines by chemical reaction with battery materials

Abstract

We demonstrate fast and efficient chemical redox insertion of lithium ions into solid FePO₄ from lithium salt solutions contaminated with other cations. The method is illustrated with sodium thiosulfate, Na₂S₂O₃, as a reducing agent that is found to have an optimum redox potential for this reaction. The method shows a very high selectivity for lithium extraction; enrichment in lithium concentration vs. other ions of more than 500 is achieved under the conditions relevant to lithium extraction from brines.